class Dog(object):
    def work(self):
        print("指哪儿打哪儿。。。")

class ArmyDog(Dog):
    def work(self):
        print("追击敌人。。。")

class DrugDog(Dog):
    def work(self):
        print("追查毒品。。。")
        super(DrugDog, self).work()

class Person(object):
    def work_with_dog(self, dog):
        dog.work()

ad = ArmyDog()
dd = DrugDog()

daqiu = Person()
daqiu.work_with_dog(ad)
daqiu.work_with_dog(dd)